Changing width and height of Image inside a datatemplate - xaml

Question

I have an image inside datatemplate. I want to change its height and width depending on certain conditions. How can I achieve that?
The XAML code I have:
<ListBox x:Name="options_stack" HorizontalAlignment="Left" Margin="198,569,0,33" Width="603" ScrollViewer.HorizontalScrollBarVisibility="Auto" ScrollViewer.VerticalScrollBarVisibility="Disabled" ScrollViewer.HorizontalScrollMode="Auto" Height="123" Style="{StaticResource ListBoxStyle}" ItemContainerStyle="{StaticResource ListBoxItemStyle}" >
<ListBox.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ListBox.ItemsPanel>
<ListBox.ItemTemplate>
<DataTemplate>
<Image x:Name="options_image" Source ="{Binding}" Stretch="Fill" Width="123" Height="123" MaxHeight="123" MaxWidth="123" Tapped="apply_accessory"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>

Answer 1

Option 1
Since you are binding source property I would create a data structure (to use as DataContext) to hold Source, Width and Height properties and then bind them:
<Image x:Name="options_image"
Source ="{Binding Source}"
Width="{Binding Width}" Height="{Binding Height}"
MaxWidth="{Binding Width}" MaxHeight="{Binding Height}"
Stretch="Fill" Tapped="apply_accessory"/>
Option 2
Another option is to create different DataTemplates and a DataTemplateSelector to apply when certain conditions are met.
DataTemplateSelector ref: http://msdn.microsoft.com/en-us/library/system.windows.controls.datatemplateselector.aspx
Option 3
If you don't like both above options you have another way of doing it. In my last work (Taskin, if you want to take a look you can see the link in my profile) I needed to show different colors for different ListViewItems. I didn't want to create a new Property in my Task model to hold the color or a TemplateSelector just for this. So I created a simple IValueConverter instead that uses an already existent Priority object property and returns its color. Then I binded it like this:
<Border Background="{Binding Priority, Converter={StaticResource priorityToColorConverter}}"/>
XAML gives you many ways to implement what you want and it is up to you to choose the best and cleanest way to solve the problem you are facing.